refactor: Webhooks (#12487)

Closes #12303

### What’s Changed
- Replace auto‐save with explicit Save / Cancel
Webhook forms now use manual “Save” and “Cancel” buttons instead of the
old debounced auto‐save/update.

- Separate “New” and “Detail” routes
Two dedicated paths `/settings/webhooks/new` for creation and
/`settings/webhooks/:webhookId` for editing, making the UX clearer.

- URL hint & normalization
If a user omits the http(s):// scheme, we display a “Will be saved as
https://…” hint and automatically default to HTTPS.

- Centralized validation with Zod
Introduced a `webhookFormSchema` for client‐side URL, operations, and
secret validation.

- Storybook coverage
Added stories for both “New Webhook” and “Webhook Detail”

- Unit tests
Added tests for the new `useWebhookForm` hook

packages/twenty-front/src/modules/settings/developers/validation-schemas/webhookFormSchema.ts

@@ -0,0 +1,31 @@
+import { isValidUrl } from 'twenty-shared/utils';
+import { z } from 'zod';
+
+export const webhookFormSchema = z.object({
+  targetUrl: z
+    .string()
+    .trim()
+    .min(1, 'URL is required')
+    .refine((url) => isValidUrl(url), {
+      message: 'Please enter a valid URL',
+    }),
+  description: z.string().optional(),
+  operations: z
+    .array(
+      z.object({
+        object: z.string().nullable(),
+        action: z.string(),
+      }),
+    )
+    .min(1, 'At least one operation is required')
+    .refine(
+      (operations) =>
+        operations.some((op) => op.object !== null && op.action !== null),
+      {
+        message: 'At least one complete operation is required',
+      },
+    ),
+  secret: z.string().optional(),
+});
+
+export type WebhookFormValues = z.infer<typeof webhookFormSchema>;